The present invention is useful in a variety of surgical procedures but is particularly useful in arthroscopic surgery of the knee and most particularly in facilitating the surgical repair or reconstruction of the anterior cruciate ligament (ACL). Sports injuries to the knee often result in tearing of the ACL. If the injured person is a professional athlete, it may be critical to full recovery and to his or her ability to further compete professionally to repair or reconstruct the ligament so that is mimics as much a possible the function of the original ACL.
The anatomically correct procedure would be to make a double band graft where the graft is divided into the two major bands of the ACL, i.e., the anterior medial band and the posterior lateral band, securing each band to the femur. However, it is very difficult to design an operation to provide such an arrangement. Most surgical graft procedures have utilized a single graft joined at one center point on the tibia and at one center point on the femur using bone-tendon-bone blocks taken from the patient's patella and fixed by an interference fit in drilled bone tunnels. In concept, center-to-center attachment of a single band of reasonable size is supposedly "isometric" so that the fiber does not change over its length in any position of knee flexion or extension. However, in fact, not all portions of the graft are going to be perfectly isometric, so that if the points of attachment turn out to be wrong, there is a tendency for the graft to stretch, making the knee looser than it would ordinarily be. Moreover, if the tibial attachment is too far forward, the graft can impinge against the roof of the intercondylar notch as the knee is extended, preventing the knee from straightening out. When that happens, a notchplasty may be required or the graft moved further backwards, entailing additional surgery.
In another procedure used with certain ACL tears, up to 20 sutures are placed in each of the stumps of the torn ligament. Using a drill guide, a guide pin is inserted in back of the knee and then an arthroscopic port is formed using a cannulated drill over the pin. Half of the sutures are drawn through the port, the other half through the center of the knee and around the back of the knee where they are tied to the first half. Several problems arise with such a procedure. First, the procedure requires additional dissection around the back of the knee to retrieve the sutures. Second, the sutures are drawn over tendon structure making it difficult to tie the sutures. Third, placement of the reattachment is less anatomic when you have to draw the sutures over the back of the knee than if you took them all through an anatomic attachment site.
The present invention solves the foregoing problems associated with reconstruction of the ACL as well as those associated with suture repair of the ACL. In one embodiment a convergence guide is provided in which converging guide holes allow the drilling of two pins starting at different places on the outside of the knee but converging to the same spot in the center of the knee. For example, the pins can be drilled to converge from the lateral area of the knee where a surgeon would normally be drilling a hole through the femoral condyle to retrieve sutures. The sutures could then be brought out through the separate holes on the lateral side providing a bone bridge over which the sutures could be tied.
Use of the convergence guide also facilitates a double banded graft such as used in semi-tendonosis anatomic reconstruction (known by the acronym STAR) and is also applicable to dacron grafts as well as to achilles tendon or patellar tendon cadaver grafts, all of which are well known grafts but which are difficult to perform or have the problems referred to above. The STAR procedure is based on the observation that the anterior medial band ducks under the roof of the intercondylar notch at a flatter angle than does the posterior lateral band. The anterior medial band starts further forward on the tibia but then goes at a relatively flat angle to a point further back. The posterior lateral band starts at a point further back on the tibia and goes at a relatively steep angle to a point further forward. As a result, fibers of the posterior lateral band are tighter in extension of the knee whereas fibers of the anterior medial band are tighter at 45 degrees of knee flexion. Using the convergence guide allows the two anatomic bands to be placed in such a way that the posterior lateral band can be tightened in extension and the anterior medial band can be tightened at 45 degrees of knee flexion thereby mimicking the natural disposition of these bands. The bands can then be sutured to one another and/or stapled down over the bone bridge formed by the separation of the converged holes on the lateral side of the knee.
Since different patients will require the convergence point to be located at different distances from the guide, a plurality of converging guide holes are provided. This is accomplished by means of a pair of cylindrical offset members slidably carried in respective converging cylindrical bores on the convergence guide. One offset member is used to slide over and pivot around a first guide pin that has been drilled into the bone. The other offset member is used as a guide to receive a second guide pin to be drilled so as to converge with the first pin. Each offset member contains along its length a plurality of parallel holes offset predetermined distances from each other, enabling the surgeon to choose any of a plurality of convergence distances.
In a particular embodiment, the holes in each offset member are disposed in a rectangular array of at least nine holes including a central hole, corner holes and side holes. The center-to-center distance between each of two opposite side holes and the central hole is 2 mm and the center-to-center distance between each corner hole and the central hole is 3 mm. As a result, parallel offsets of exactly 2, 3, 4 and 6 mm are available to the surgeon along with the intermediate distance of about 4.5 mm. This results in convergence distances into the bone in the range of about 30 to about 40 mm. In still another embodiment, the proximal side of the convergence guide is concave to better fit a patients knee.
By providing converging holes in slidably disposed members, the convergence guide is readily disassembled. Slots are defined entirely through the sidewall of the convergence guide to and coextensive with respective cylindrical bores, each slot being wider than the thickness of the guide pin. The convergence guide is removed while leaving the converging pins in place by sliding the offset members out of their bores and then withdrawing the convergence guide while the pins pass through the slots.
Other problems that arise in the course of arthroscopic surgery relate to difficulties in properly placing or aligning guide pins. The surgeon attempts to locate the pins so that they converge at the inner surface of the knee, but initial placement will generally require some guessing and a poor estimate of the convergence point may require redrilling the pin. Even a single pin can be badly placed or be misaligned due to the tendency of the drill to wander while drilling. Taking the pin out and redrilling is difficult because of the tendency of the pin forming the new hole to slide into the old hole during drilling.
Prior mechanical approaches to this problem are not quite satisfactory. One device, known as an Acufex, has a lug formed with a nubbin on one side that is placed in the bad hole after the pin is removed. The lug has a guide hole offset from the center of the nubbin by 3 mm which can pivot around in any direction to drill a parallel hole 3 mm from the old hole. One problem is that it is often difficult to find the small hole left when the pin is removed. Another problem is that the surgeon has only the option of moving the pin the single fixed distance of 3 mm from the original hole, which limits the surgeon's choices.
Another device is known as the Lemoire offset and has three parallel holes in a triangular array, each hole being 3 mm center-to-center from each other. The offset is slid onto the bad pin and then pivoted around the pin to a desired location, but limited to 3 mm from the original hole where a new pin is drilled parallel to the first pin. As with the Acufex, the surgeon has only the limited option of moving the pin the single fixed distance of 3 mm from the original hole.
These problems are alleviated by another embodiment of this invention in which one of the cylindrical offset members is used as a unique offset guide to enable a second pin to be drilled through a bone in close parallel proximity to a first pin disposed in the bone. The cylindrical offset member is fitted with a clamp handle and is used by sliding the offset member over the badly placed pin through one of the parallel holes and then pivoting it in a desired direction. A new pin is then placed at a desired offset distance and drilled into the bone in parallel proximity to the first pin without the danger of sliding into the first hole which is still occupied by the first pin. After successfully inserting the second pin into the bone, the first pin can be removed. The unique array of parallel holes allows great flexibility to the surgeon in correcting poor pin placement.